Inflation method and apparatus



Filed Ndv.

FIG. 11

rum NITRAT comaus'nou j PRODUCTS) 1/ com uoum REFRIGERANT uoumen FLUOR-HOT GASES (as. AMMON- E FIRST STAGE j i inf i 2 a x 4 91L ,1 MASS FLOWmom OBJECT 4 PRESSURE M PSIG (m A PRESSURE v sscorw STAGE a INATEDHYDROCARBON) o NE H0 ET AE RYER G D OA SFGG WW NE 3% CAJL ATTORNEYSUnited States Patent 3,460,747 INFLATION METHOD AND APPARATUS Charles J.Green, Vashon Island, Alan K. Forsythe,

Seattle, John W. Goode, Mercer Island, and Lyle D. Galbraith, Redmond,Wash., assignors to Rocket Research Corporation, Redmond, Wash., acorporation of Washington Continuation-impart of application Ser. No.678,565,

Oct. 27, 1967. This application Nov. 5, 1968, Ser.

Int. Cl. F04f 5/22, 5/48; F16k 15/20 US. Cl. 230-104 5 Claims ABSTRACTOF THE DISCLOSURE Gases under pressure are continuously delivered at arate characterized by substantially no pressure droop into the firststage of a two-stage ambient air aspirator connected to a gas confiningtype inflatable, to serve as the aspirating fluid for the first stage.The first stage effluent is used as the aspirating fluid for the secondstage and the second stage effluent is directed into the inflatableuntil it is substantially full. Thereafter, the ambient air path for thesecond stage is valved shut and the first stage effluent alone is usedto complete inflation.

CROSS REFERENCE TO RELATED APPLICATIONS This is a continuation-impart ofour copending application Ser. No. 678,565, filed Oct. 27, 1967, andentitled Two Stage Inflation Aspirators.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to inflation aspirators, and more particularly to multistageaspirators adapted for rapid inflation of various inflatable objects;such as escape chutes, rafts, and the like.

Description of the prior art A rapid inflation rate is a requirement ofmany inflatable devices, particularly those used with emergency objects,such as escape chutes and rafts.

Prior art aspirating devices aiming towards rapid in flation ofinflatable objects have generally taken one of two forms. The first formis exemplified by the aspirator shown in the patent to Neigel,2,859,908. An aspirating gas is introduced as a high velocity streaminto a venturi nozzle adapted to discharge into the object beinginflated. The upstream end of the nozzle is open to the surrounding airand the high vleocity gas stream creates a suction to draw or aspirateambient air into the stream for the purpose of increasing its volume.When the object is sufliciently inflated, and delivery of the aspiratinggas has ceased, a check valve in the nozzle is closed by back pressureto prevent deflation.

A second form of inflation aspirator is shown in the patent to Crawfordet a1. 2,772,829. It is adapted for use in installations wherein thecombined stream of aspirating gas and aspirated air, although of a highvolume, is of an insuflicient pressure to fully inflate the object. Acheck valve is provided to be closed by back pressure when the pressurein the object being inflated reaches the pressure of the air and gasstream. Aspiration of ambient air is stopped. However, the gas flow iscontinued and it, by itself being of a higher pressure than the gases inthe object, continues to inflate the object.

SUMMARY OF THE INVENTION This invention includes the technique of usinga twoice stage aspirator to inflate a gas confining flexible-walledobject. The aspirating fluid for the first stage is obtained from aconstant pressure source and the stream of aspirating fluid andaspirated air leaving the first stage nozzle is used as the aspiratingfluid for the second stage nozzle. In this manner a high volume, lowpressure fluid stream is used to inflate the object up to a desiredpressure level less than the final pressure. When this lower level isreached the second stage of the aspirator is fluid choked or valved shutand inflation is completed by the eflluent of the first stage nozzleonly.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagram of aconstant pressure gas source, a two-stage aspirator, and an inflatableobject;

FIG. 2 is graphical illustration showing the pressureflowcharacteristics of the aspirator;

FIG. 3 is an isometric view of one form of two stage aspirator;

FIG. 4 is an axial section view of the aspirator of FIG. 3, both stagesactive;

FIG. 5 is an axial section of such aspirator with only the first stageactive;

FIG. 6 is an axial section view of another form of two-stage aspirator;and

FIG. 7 is a cross-sectional view of the aspirator shown by FIG. 6.

DESCRIPTION OF THE PREFFERED EMBODIMENTS Referring to FIG. 1, a streamof hot gases (e.g. the products of combustion of an ammonium nitratetype solid fuel grain) and a stream of a cold liquid refrigerant (e.g. apressure liquified fluorinated hydrocarbon) are separately andcontinuously introduced into a mixing chamber M for flow through mixing.In chamber M the refrigerant is vaporized with the heat of vaporizationbeing supplied by the hot gases. A high pressure, relatively cool,gaseous effluent leaves chamber M and is the primary or aspirating fluidfor the aspirator 10. The pressure of such cool fluid is dependent onthe delivery rates of the hot gases and the refrigerant. According tothe invention the hot gases and the refrigerant are delivered atconstant or progressively increasing rates, so that the inflating fluidnever experiences a pressure droop. A progressive increase in the flowrates causes a progressive increase in the pressure of the working fluidtending to enter the inflatable in opposition to a progressivelyincreasing back presure.

Cool gas generators for generating and supplying a no droop aspiratingfluid for the first stage are disclosed in copending applications Nos,608,152 and 682,730, respectively filed on Jan. 9, 1967 and Nov. 7,1967. Application Ser. No. 608,152, issued as US. Patent No. 3,431,- 742on Mar. 11, 1969. Application Ser.. No. 682,730 issued as US. Patent No.3,431,743, also on Mar. 11, 1969. The disclosures of these patents arehereby expressly incorporated herein by this specific reference.

The aspirating fluid is discharged through a plurality of orifices 17into a first stage nozzle 18, the downstream end of which is initiallyclosed by a circular inner check valve 20. A second stage nozzle 22 ispositioned downstream of the first stage nozzle and has an air intakeopening closed :by an annular outer check valve 24. The gas streamsdischarging from the orifices 17 entrain air into the first stage nozzle18. The effluent of the first stage nozzle flows into the second stagenozzle 22 and becomes the aspirating fluid for the second stage.Inflation takes place at a rapid rate due to the high volume of airdischarged from the second stage. When the pressure builds up in theobject O (cg. an escape U slide) to a predetermined level, the outercheck valve 24 is closed by back pressure and the object is furtherinflated by the first stage nozzle 18 alone. When the object is fullyinflated, gas flow is ceased and the back pressure in the object closesthe inner check valve 20 as well, and the two valves 20, 24 togetherprevent deflation.

The first stage nozzle 18 has a cylindrical throat 26 formed integrallywith a smoothly rounded, diverging flange 28 that defines an air inlet29. The inlet manifold 15 extents diametrically across the air inlet andis secured to the flange to provide structural strength. The orifices 17are aligned diametrically on the downstream Side of the manifold.

The second stage nozzle 22 includes a cylindrical throat 3t integrallyformed with a rounded, outwardly diverging inlet flange 32 that definesa second air inlet 33. An annular mounting ring 34 is secured to aninlet flange and is secured to the fabric 38, or the like, of an objectto be inflated, such as an airplane escape chute, for example. Thesecond stage nozzle is connected to the first stage nozzle by threeequidistantly spaced structs 40 that are secured, as by welding, to thesecond stage inlet flange and the outside surface of the first stagenozzle throat 26. The inlet flange 32 is provided with an inwardlydirected peripheral lip 42 that serves as a valve seat in a manner to behereinafter described.

The inner check valve 20 is best shown in FIG. 3 and includes a circularmember or flap 44 of neoprene, rubber, or other flexible, resilientmaterial, and is of a diameter slightly greater than the inside diameterof the throat 26. A pair of centrally bored bosses 46 are bonded orotherwise secured to the downstream surface of member 44 and are alignedalong its vertical diameter. The bosses receive a pin 48 which issecured in spaced holes by any suitable means, in the throat 30 of thesecond stage nozzle 22. The pin serves as a support about which the sidesegments of the member 4 may pivot.

A pair of semi-circular strengthening members 52 are secured, as bybonding, to each side of the downstream surface of the member 44. Thesemembers 52 are preferably of aluminum or any other suitable relativelyrigid material. Each member 52 extends radially outwardly almost to theperipheral edge of the member 44. In effect, the check valve amounts totwo hinged together rigid flaps with a resilient peripheral sealingedge,

The outer check valve 24, which closes off the second air inlet 33,includes an annular resilient, flexible member 54 of the same flexiblematerial as the circular member 44. A pair of centrally bored bosses 56are bonded to the downstream surface of the annular member 54. Thebosses are diametrically aligned and receive the pin 48. A pair ofsemi-annular strengthening members 58 are secured, as by bonding, to thedownstream surface of the member 54 and extend almost to the inner andouter edge of such member 54. These members 58 function in the identicalmanner as the members 52. The upstream outer peripheral edge 60 of themember 54 abuts against the lip 52 of the inlet flange 32. The inneredge 62 of the member 54 extends radially inwardly beyond the innercircumferential surface of the throat 26 of the first stage nozzle 18and serves as a seat for the inner valve 20.

When air in being aspirated in both stages, the side parts of theannular member 54 are folded together downstream. As the object isfilled a back pressure is developed, and eventually it closes theannularvalve member 54 and the second stage of the aspirator ceases tooperate. Inflation is then completed by the primary aspirator alone.Following completion of the inflation the inner circular valve member 44is also closed by back pressure and it and the annular valve 24 functiontogether as check valves to hold the fluid in the object.

The effect of the two-stage aspiration is best shown in FIG. 2, whereinthe line ABD represents the flow rate of the combined first and secondstages if no second stage shutoff valve were to be provided. The linesshown in the graph of FIG. 2 actually represent a mass flow ratio aconstant flow of aspirating fluid i t As an example, assume theaspirating fluid source produces a supply of aspirating fluid fu at aconstant rate of one pound mass per second. If the second stage is beingused, that is as indicated by the line ABD the initial mass flow rate ofaspirated air is at a ratio of 3.2 and thus is 3.2 l pound mass persecond yielding a total fluid flow rate of approximately 4.2 pounds massper second. At a ratio of 1 along the same line ABD the aspirated airflow rate is also 1 pound mass per second so that total flow rate atthis ratio is 2 pounds mass per second. This convention of referring toflow rate rather than to ratio will be followed that a high volume ofmixed air and gas is initially introduced into the object but thatpressure never exceeds 2 p.s.i.g. In the embodiment just described, thearea of the air inlet of the combined nozzle stages is approximately 4/2 times the area of the air inlet of the first stage nozzle alone.

The line EBC represents the flow rate if only the single stage were tobe used, as was heretofore customary, The single stage can reach asignificantly greater pressure. However, the initial flow rate issubstantially less than with two stages.

By the use of the check valve 24 in the second stage nozzle 22 the flowrate curve follows the solid line ABC. Thus, a high volume initial flowrate is produced up until point B where the back pressure is suflicientto close the outer check valve 24. The curve then follows the flow ratefor the single stage nozzle reaching a pressure of over 4 p.s.i.g. inthe example presented. Since the first 60% of inflation is at a pressureslightly greater than atmospheric, the large volume will greatlyincrease the speed at which this amount of inflation is reached, Forexample, in the installation to which the graph relates the initial useof the second stage reduced the timeof filling from 5 to 3 seconds or apercentage increase of Aspirator 70 shown by FIGS. 6 and 7 comprisesfirst and second stages 18, 22, respectively. The first stage includes atubular nozzle 26 and an injector 15' for the aspirating fluid. Pipe 16'is connected to the mixing chamber M. The tube 26 is situated inside alarger and longer tube 30. Three evenly spaced radial support plates 72rigidly interconnect the tubes 26', 30.

The check valve for the annular second stage path comprises acylindrical sleeve 74 of rubberized fabric or the like. Sleeve 74 isattached at its outer end 76 t0 the outer end of tube 30'. The supportplates 72 are secured to the tube 30', such as by welding at points 78.The plates 72 are cut away in the region of the seal member 74, so thatin each of such regions the member 74 is clamped between an outer radialend surface of the members 72 and a contiguous inner portion of the Wall30.

During second stage aspiration a sleeve 74 is generally cylindrical inform and closely hugs the inner surface of the tube 30'. When back flowcommences, the strongest flow is relatively along the inner surface ofwall 30'. It catches the loose downstream edge portions of the member 74between the support plates 72 and moves such edge portions radiallyinwardly. Pockets are formed circumferentially between the plates 72 andradially between member 74 and tube 30'. The forward ends of the pocketsare closed by virtue of the all-around connection of the member 74 tothe tubular wall 30' at 76. The back flowing gases fill up the pockets.As shown by broken lines in FIGS. 6 and 7, the back flowing fluid causesthe member 74 to move in and closely hug the outer surface of inner tube26'. Since the pressure in the pockets acts in all directions theportions of member 74 on opposite side of the support plates 72 arepressure held against the support plates 72.

The circumferential lengths of the portions of member 74 which hug theinner tube 26' plus the radial lengths of the portions of member 74which hug the supports 72 all together substantially equal thecircumferential length of member 74 when it is out against the outertube 30'. This is because the circumference at the inside wall of tube30' is greater than the circumference at the outer surface of tube 26'by an amount equal to 21r times the difference in radius at these twolocations, i.e., the difference in circumference is 6.28 times thedifference in radius. The amount of material required to hug both wallsof each of the three struts 72 is equal to 6 times the difference inradius. There is a slight excess of circumferential length in thematerial 74 which is equal to 6.28 times the difference in radius, i.e.,the radial length of the member 72. This excess length is distributedabout the outer surface of tube 26' and is easily accommodated so that asubstantial tight fit exists between the inner surface of member 74 andthe outer surface of tube 26' between the struts 72, and the two sidesurfaces of the struts 72.

In this form the tube 30 is manufactured to include a circumferentialshoulder 80. A single large check valve 82 is supported in the tube 30'generally in a common plane with the downstream surface of shoulder 80.The valve 82 is supported by a support pin 84 which extends across, andis anchored at its opposite ends to, the tube 30'. A transverse stop pin86 may be provided downstream of pin 84 in the same axial plane with pin84. When valve 82 is closed its peripheral region abuts the radialdownstream surface of shoulder 80. Check valve 82 functions like checkvalve 20 in the embodiment of FIGS. 3-5, and also serves to preventleakage from the object 0 once it has been inflated.

What is claimed is:

1. In combination:

an inflation aspirator comprising an inlet tube of said inflatable for agas confining type inflatable having an ambient air inlet and a combinedfluid outlet, an injector for delivering an aspirating fluid into saidinlet tube, and the improvement characterized by tubular wall meansdividing the interior of the inlet tube into first and second stagepassageways, each having an ambient air inlet, with said injector beingpositioned to discharge directly into the first stage passageway, andwith said first stage passageway being positioned to discharge into saidsecond stage passageway, so that the mixture of aspirating fluid andaspirated ambient air discharging from said first stage passagewayfunctions as an aspirating fluid for causing second stage aspiration inthe second stage passageway, and check valve means in an ambient airinlet portion of said second stage passageway, arranged to close inresponse to a predetermined back pressure in the inflatable and in thatmanner render the second stage of the aspirator ineffective, withinflation thereafter being completed by the first stage of the aspiratoralong;

a source of primary aspirating fluid comprising a gaseous fluideminating reaction chamber, and means for controlling the efiiuentpressure from said reaction chamber so that such eflluent experiences nopressure droop; and

means for continuously delivering such effluent to said injector toserve as a no pressure droop primary aspirating fluid stream.

2. In an inflation system for a gas confining type inflatable, themethod of delivering a cool gas energy stream at a rate of flowcharacterized by substantially no pressure droop, into an ambient airaspirator connected to the inflatable, to pump air into the inflatable,and after the inflatable is partially distended, disabling at least aportion of the aspirator while continuing to deliver the generated coolgases into the inflatable without pressure droop, to complete distentionof and pressurize the inflatable.

3. In an inflation system for a gas confining type infiatable, themethod of continuously delivering a stream of cool gases under pressureinto the first stage of a two-stage ambient air aspirator discharginginto an infiatable, and using the stream of such cool gases combinedwith the ambient air entrained into said first stage as the pumpingfluid to operate the second stage of the aspirator during at least mostof the time the inflatable is being filled, and then rendering thesecond stage of the aspirator ineffective responsive to pressure withinthe inflatable, and pressurizing the inflatable to the extent desired bycontinuing to deliver the cool gases through the first stage of theaspirator without pressure droop.

4. A method of inflating an object comprising the steps of:

directing a stream of an aspirating fluid generally axially through afirst stage nozzle which about said stream is open to ambient air, toentrain ambient air into said nozzle; directing the effluent of thefirst stage nozzle axially through a second stage nozzle which at leastpartially about said first stage nozzle is open to ambient air, and isarranged to discharge into an inflatable object, for the purpose ofentraining an additional quantity of ambient air into the second stagenozzle;

ceasing second stage entrainment of ambient air substantially when theback pressure in the object equals the pressure of the second stageambient air stream;

completing inflation of the object by use of the entraining fluid andthe first stage entrained ambient air stream alone; and

closing all avenues through the nozzles once inflation has beencompleted.

5. The method of claim 4, comprising automatically closing said avenuesby back pressure closure of check valve means in the nozzles.

References Cited UNITED STATES PATENTS 1,367,208 2/1921 Schmidt 103-2582,096,226 10/1937 Crosthwait 230-92 2,296,122 9/1942 Squassoni 230-452,399,670 5/1946 Preggang 230-92 2,887,120 5/1959 De See 137-2233,042,290 7/ 1962 Fraebel 230-95 3,204,862 9/ 1965 Hadeler 230-953,338,266 8/1967 Zilka et a1. 103-263 X 3,358,909 12/1967 Mansson et al230-45 3,370,784 2/1968 Day 137-223 X 3,395,647 8/1968 Clabaugh 103-272X DONLEY J. STOCKING, Primary Examiner W. J. KRAUSS, Assistant ExaminerUS. Cl. X.R.

